The present invention relates to the discovery, identification and characterization of novel human polynucleotides that encode proteins sharing structural similarity with transporter proteins. The invention encompasses the described polynucleotides, host cell expression systems, the encoded proteins, fusion proteins, polypeptides and peptides, antibodies to the encoded proteins and peptides, and genetically engineered animals that lack at least one of the disclosed genes, or over express the disclosed genes, antagonists and agonists of the described proteins, and other compounds that modulate the expression or activity of the proteins encoded by the disclosed genes that can be used for diagnosis, drug screening, clinical trial monitoring, and/or the treatment of physiological or behavioral disorders.
Transporter proteins are used to facilitate the translocation of certain molecules either into or out of the cell. Often, such transporters work by xe2x80x9cpumpingxe2x80x9d ions across the cell membrane and co-transporting specific molecules (amino acids, amino acid derivatives and precursors, dicarboxylates, inorganic molecules, etc.) across the membrane. Such mechanisms play important roles in maintaining cellular and metabolic homeostasis, neuron function, signaling, and drug resistance. As such, transporter proteins constitute compelling targets for the development and study of novel therapeutic agents.
The present invention relates to the discovery, identification and characterization of nucleotides that encode novel transporter proteins, and the corresponding amino acid sequences of the described novel transporter proteins (NTPs). The NTPs described for the first time herein, are transmembrane proteins that span the cellular membrane and are involved in translocating molecules across membranes. The described NTPs share structural similarity with a variety of transporter proteins. The sequences encoding the NTPs were initially identified via chimeric gene trap transcripts generated in human cells. The novel human NTPs described herein, encode proteins of 627, 627, 581, 627, 627, 581, 626, 626, 580, 626, 626, 580, 672, 672, 258, and 258 amino acids in length (see SEQ ID NOS: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, and 32 respectively). The described NTPs have hydrophobic leader sequences and transmembrane regions (of about 20-30 amino acids) characteristic of transporter proteins.
The invention encompasses the nucleotides presented in the Sequence Listing, host cells expressing such nucleotides, the expression products of such nucleotides, and: (a) nucleotides that encode mammalian homologues of the described NTPs including the specifically described human NTP genes; (b) nucleotides that encode one or more portions that correspond to functional domains of a NTP, as well as the polypeptide products specified by such nucleotide sequences, including but not limited to the novel regions of any extracellular domain(s) (ECD), one or more transmembrane domain(s) (TM), and the cytoplasmic domain(s) (CD); (c) isolated nucleotides that encode mutants, engineered or naturally occurring, of the described NTPs in which all or a part of at least one of the domains is deleted or altered, and the polypeptide products specified by such nucleotide sequences, including but not limited to soluble receptors in which all or a portion of a TM is deleted, and nonfunctional receptors in which all or a portion of a CD is deleted; (d) nucleotides that encode fusion proteins containing the coding region from a NTP, or one of its domains (e.g., an extracellular domain) fused to another peptide or polypeptide.
The invention also encompasses agonists and antagonists of the NTPs, including small molecules, large molecules, mutated NTPs, or portions thereof, and antibodies, as well as nucleotide sequences that can be used to inhibit the expression of the described NTPs (e.g., antisense and ribozyme molecules, and gene or regulatory sequence replacement constructs) or to enhance the expression of the described NTP genes (e.g., expression constructs that place the described genes under the control of a strong promoter), and transgenic animals that express a NTP transgene or xe2x80x9cknock-outsxe2x80x9d (which can be conditional) that do not express a functional NTP (see, for example, PCT Applic. No. PCT/US98/03243, filed Feb. 20, 1998, herein incorporated by reference). In addition to knock-outs, an additional aspect of the present invention includes animals having genetically engineered mutations in at least one of the described genes that modify the activity or expression of the NTP (i.e., point mutations, over-expression mutations, etc.).
Further, the present invention also relates to methods for the use of the described NTP genes and/or NTPs for the identification of compounds that modulate, i.e., act as agonists or antagonists, of NTP gene expression and or NTP activity. Such compounds can be used as therapeutic agents for the treatment of various symptomatic representations of biological disorders or imbalances.
The Sequence Listing provides the sequence of the described NTP polynucleotides, and the amino acid sequences encoded thereby.